Process for rendering textiles and other fibrous materials oil-,water-and soil-repellent



United States Patent Office 3 ,5 18,1 14 Patented June 30, 1970 US. Cl.117-161 1 Claim ABSTRACT OF THE DISCLOSURE An adduct ofhexafluoroacetone and an alkali metal fluoride is reacted with a2,3-dihalo-n-propyl acrylate (or methacrylate) to produce 2,3-bis(heptafluoroisopropoxy)- n-propyl acrylate (or methacrylate). Theproducts are useful in monomeric, and especially polymeric, form forenhancing the oil-, water-, and soil-repellency of fibrous materials,e.g., textiles.

This application is a division of our co-pending application, Ser. No.555,703, filed June 7, 1966, now Pat. No. 3,480,664.

A non-exclusive, irrevocable, royalty-free license in the inventionherein described, throughout the world for all purposes of the UnitedStates Government, with the power to grant sublicenses for suchpurposes, is hereby granted to the Government of the United States ofAmerica.

This invention relates to and has among its objects the provision of neworganic compounds, namely, fluorinated esters of acrylic acid andmethacrylic acid, in both monomeric and polymeric form. The objects ofthe invention also include methods for synthesizing these compounds,procedures for treating fibrous materials with the compounds, and thetreated materials as new articles of manufacture. Further objects of theinvention will be evident from the following description wherein partsand percentages are by weight unless otherwise specified.

THE NEW COMPOUNDS The novel monomers of the invention are represented bythe following formulas:

In the above formulas, R represents H or CH Generically, the monomers ofthe invention may be represented by the structure:

0 or -b-or wherein:

R is H or CH and n is zero or 1.

A particularly critical aspect of the compounds of the invention is thepresence of the heptafluoroisopropyl radicaland especially in the factthat it contains a fluorine group in alpha position, that is, on thesecvondary carbon (marked by an asterisk in Formula IV, above). Theunique structure of this radical provides the advantage that it confersa greater degree of oleophobicity for a given number of fluorinatedcarbon atoms than with a straight-chain arrangement of CF groups. Infact, our investigations have shown that three fluorinated carbon atomsin our arrangement provide a degree of oleophobicity equivalent to 6 or7 fluorinated carbon atoms in a straight chain. A further critical pointof the compounds of the invention is that they contain two of theheptafluoroisopropyl groups per molecule, whereby the compounds areoutstandingly effective in conferring oleophobic properties to fibrousmaterials such as textiles treated therewith. Another important aspectof the compounds of the invention is that the heptafluoroisopropylgroups are effectively isolated from the acrylic (or methacrylic) estermoiety by the 3-carbon atom bridging structure which may be in a normalor iso configuration, i.e.:

-CH2CHC2-O l (where n is 1) or 1 (where n is 0).

As a result the compounds are stable: the ester group resists hydrolysisand fluorine shifts do not occur. In contrast, compounds which containan acyl group directly linked to a heptafluoroisopropoxy group aresusceptible to a fluorine shift which results in splitting the compoundwith the formation of hexafluoroacetone and the corresponding acylfluoride. Moreover, the aforesaid isolating structure permits thecompounds of the invention to undergo typical polymerization reactions,unaffected by the fluorine-containing groups. Accordingly, the compoundscan be readily converted into various polymeric derivatives useful for awide variety of uses, especially for treatment of textiles and otherfibrous materials. A further important point is that the aforesaidbridging group, containing only three carbon atoms, does not annul theoleophobic effect of the heptafluoroisopropyl groups. Thus when thepolymers of the invention are applied to (or formed on) textiles orother fibrous material, the fluorinated groups are still relativelyclose to the polymer backbone, whereby they can provide a high degree ofoleophobicity to the treated fibrous substrate.

Among the various compounds of the invention, we especially prefer theacrylate esters as yielding particularly good oil-, water-, andsoil-repellant finishes on textiles.

PREPARATION OF THE NEW COMPOUNDS In preparing the compounds of theinvention, an adduct of hexafluoroacetone and an alkali metal fluorideis reacted with a dihalo- (normal or iso) propyl acrylate ormethacrylate. The synthesis may be readily visualized from the followingequation:

In the above formulas:

M is an alkali metal, R is H or CH n is zero or 1, and X is Cl, Br, orI.

It is evident from the foregoing formulas that the synthesis is a simpleetherification involving replacement of the halo groups (X, above) bythe heptafluoroisopropoxy groups and elimination of alkali metal halide.The desired etherification is accomplished simply by contacting thereactants. The temperature at which the reaction is conducted is not acritical factor and may vary, for example, from to 150 C. Generally,temperatures of about 70 to 100 C. are prepared to increase the rate ofreaction, yet without danger of decomposition. To avoid hydrolysis ofthe reactants, particularly the adduct, the reaction is carried outunder anhydrous conditions. To attain good contact between the reactantsit is preferred to employ an inert solvent as, for example,acetonitrile, tetrahydrofuran, tetramethylene sulphone, dimethyl etherof diethylene glycol, etc. After completion of the reaction, the productmay be separated by dropping the reaction mixture into an excess ofwater, separating the organic material and subjecting it to distillationunder reduced pressure.

As explained above, one of the reactants in the synthesis 1 is an adductof hexafiuoroacetone and an alkali metal fluoride. These adducts, whichalso may be termed fluorocarbinolates, are readily prepared by reactinghexafluoroacetone with an alkali metal fluoride, such as sodium, cesium,or potassium fluoride, as disclosed in our copending application Ser.No. 398,129, filed Sept. 21, 1964, now Patent 3,384,628, granted May 21,1968.

PREPARATION OF POLYMERS The monomeric compounds described hereinabovemay be employed as intermediates to prepare useful polymers, includingboth homoand co-polymers. The polymers are readily prepared byapplication of conventional polymerization techniques. Typically, thepolymerizable monomer of the invention (per se, or admixed with adifferent vinyl monomer) is heated at about -120 C. in the presence of acatalytic amount of a persulphate such as sodium persulphate, a peroxidesuch as benzoyl peroxide, an azo polymerization initiator such asa,a'-azobisisobutyronitrile, or a redox catalyst system (typically, acombination of a reducing agent such as ferrous sulphate, hydrazinesulphate, sodium bisulphite, etc. and an oxidizing agent such ashydrogen peroxide, benzoyl peroxide, sodium peracetate, sodiumpersulphate, etc.). The polymerizations may be conducted in bulk, in thepresence of an inert solvent, or in aqueous emulsions. As noted above,the polymer may be a homopolymer, that is, one consisting of recurringunits of the monomer of the invention, or it may be a copolymercontaining such units interspersed with units derived from a differentvinyl monomer, such as ethylene, propylene, styrene, vinyl chloride,acrylonitrile, methyl acrylate or methacrylate, acryl amide,methacrylamide, vinyl acetate or stearate, butadiene, and the like.

The polymers of the invention contain recurring units of the structure:

n is zero or 1 As mentioned above, copolymers are included within theambit of the invention and in such case the above repeating units wouldbe interspersed with units of a different polymerizable monomer. Forexample, if the coreactant were styrene, the copolymer would contain theabove repeated units plus repeating units of the structure:

TREATMENT OF FIBROUS SUBSTRATES The compounds described herein areparticularly useful for the treatment of fibrous materials, such astextiles, in order to improve their properties, e.g., to improve theiroil-, water-, and soil-repellancy. In practicing this phase of theinvention, a polymer is prepared as described above and applied to thefibrous material. The polymer may be a homopolymer, that is, oneconsisting of recurring units of a monomer in accordance with theinvention. Moreover, it may be a copolymer, that is, a polymercontaining recurring units of a monomer in accordance with the inventioninterpersed with recurring units derived from one or more differentpolymerizable ethylenically-unsaturated monomers. The polymers (h'omoorco-polymers) are applied to the fibrous material in conventional manner.Typically, the polymer is dissolved in an inert volatile solvent, e.g.,benzotrifluoride, 1,3-bis-trifl-uoromethyl benzene, ortrichlorotrifluoroethane. The resulting solution is applied to thefibrous material by a conventional dip and pad technique or by anAerosol spray. By varying the concentration of the polymer in solutionand the amount of solution applied, the amount of polymer deposited onthe material may be varied. Typically, the amount of polymer may be from0.1 to 20%, based on the weight of fibrous material but it is obviousthat higher or lower proportions can be used if desired. Usually, in

treating textiles such as fabrics, the amount of polymer is limited toabout 0.1 to to attain the desired repellency without interference withthe hand of the textile. In an alternative procedure, the polymers areapplied to the fibrous material in the form of an aqueous emulsion.

After application of the polymer solution, the treated fibrous substrateis subjected to a conventional curing operation in order to bond thepolymer to the fibers. As an example of such treatment, the fibrousmaterial is heated in the range of about 50 to 150 C. for a period of 5to 60 minutes. The solvent (from the polymer solution) may be evaporatedin a separate step prior tocuring or it may simply be evaporated duringthe curing operation.

Fibrous materials treated with the polymers of the invention display anenhanced resistance to becoming soiled because they repel both waterandoil-borne soils and stains. Particularly important is conferring highresistance to soiling by oily materials is the double fluorinatedisopropyl moiety of the polymers, most importantly the fact that thereis a fluorine in the alpha position (the secondary carbon atom). Anothersignificant point is that the enhancement of soil repellency is attainedwithout detriment to other properties of the textile. In particular, thetreat ment does not impair the hand of the textile. In fact, the hand isusually improved in that the textile is softer and more supple. Anotherpoint is that the improvements rendered by the process are durabletheyare retained despite laundering and dry-cleaning of the product.

Although the preformed polymers are usually applied to the fibrousmaterial, the monomers may be applied as such in the form of a vapor, inthe pure liquid form; or from solution in an inert volatile solvent. Topromote polymerization of the monomer in situ on the fibrous material,one applies ionizing radiation, a persulphate, a peroxide, an azopolymerization initiator, or a redox catalyst system. Where suchpolymerization catalysts are used they may be incorporated With themonomer and the admixture then applied to the textile or the catalystmay be applied to the textile before or after application of themonomer. To promote the polymerization and the bonding of the polymer tothe fibers, a heatcuring step as described above is preferably employed.

The invention may be utilized for improving the properties of all typesof fibrous materials, for example, paper; cotton; linen; hemp; jute;ramie; sisal; cellulose acetate rayons; cellulose acetate-butyraterayons; saponified acetate rayons; viscose rayons; cuprammonium rayons;ethyl cellulose; fibers prepared from amylose, algins, or pectins; wool;silk; animal hair; mohair; leather; fur, regenerated protein fibersprepared from casein, soybean, peanut proteins, zein, gluten, eggalbumin, collagen, or keratins; nylon; polyurethane fibers; polyesterfibers such as polyethylene teraphthalate; polyacrylonitrile-basedfibers; or fibers of inorganic origin such as asbestos, glass, etc. Theinvention may be applied to textile materials which are in the form ofbulk fibers, filaments, yarns, threads, slivers, roving, top, webbing,cord, tape, woven or knitted fabrics, felts or other non-woven fabrics,garments or garment parts.

EXAMPLES The invention is further demonstrated by the followingillustrative examples. 1

The expression diglyme used herein is an abbreviation for the dimethylether of diethylene glycol.

The tests described in the examples were carried out as follows:

Oil repellency.-Tl1e 3M repellency test described by Crajack andPetersomTextile Research Journal 32, pages 320-331, 1962. Ratings arefrom 0 to 150, with the higher values signifying the greater resistanceto oil penetration.

Water repellency.-AATC spray test, method 22-1952. Ratings are from 0 to100, with the higher values signifying greater resistance to waterpenetration.

Example 1 (A) Preparation of 2,3-dibromo-n-propy1 acrylate Thirty-sixgrams (0.4 mole) of :acryloyl chloride were reacted with 65.4 grams (0.3mole) of 2,3-dibromopropanel at 60 C. for 4 hours, using a nitrogenpurge to remove gaseous HCl. Distillation yielded 55 grams of2,3-dibromo-n-propyl acrylate, B.P. 103/4.5 mm., N 1.5195.

(B) Preparation of 2,3-bis(heptafluoroisopropoxy)-npropyl acrylate- Intoa 1-liter, 3-necked flask were placed 44 grams (0.76 mole) of anhydrousKF and 400 ml. of dry diglyme. The mixture was stirred and 125 grams(0.76 mole) of hexafluoroacetone gas (CF -CO-CF was added at such a ratethat the condensed gas dripped slowly from an attached Dry-Icecondenser. After the addition of hexafluoroacetone was completed, thereaction mixture was stirred for an additional period (about /2 hr.)until formation of the adduct- CF F (J-0K F3 was complete, as evidencedby the disappearance of dispersed KF.

Then, 53 grams (0.19 mole) of 2,3-dibromo-n-propyl acrylate were addedin one shot and the mixture heated at 75 C. for 46 hours. At the end ofthis time, the resulting slurry was poured into 500 m1. of cold water.The lower fluorocarbon layer was collected and washed three times withadditional water. The washed liquid (60 grams) was dried over CaSO anddistilled. The distilled product (B.P. -90 C. at 4-6 mm. Hg) containedca. 30% of the desired ester, 2,3-bis-(heptafluoroisopropoxy)-n-propylacrylate; 20% of mono-addition product (2-bromo-3-heptafiuoroisopropoxy-n-propyl acrylate, or 3-bromo-2-heptafluoroisopropoxy-n-propyl acrylate, or a mixture of the two); and50% of unreacted dibromo-acrylate. A quantity of pure 2,3bis(heptafluoroisopropoxy)-n-propy1 acrylate was obtained by preparativegas chromatography, N 1.3335.

Analysis.Calculated for C F H O (percent): C, 29.8; H, 1.7. Found(percent): C, 29.7; H, 1.5.

Example 2 (A) Preparation of 2,2dichloroisopropyl acrylate The acrylatewas prepared according to the procedure described in Example 1, part A,using 64 grams (0.5 mole) of 1,3-dichloropropanol and 63 grams (0.7mole) of acryloyl chloride. The product (64 grams) was purified bydistillation-B.P. 72-74 C. at 4.5 mm. Hg, N 1.4708.

(B) Preparation of 2,2 bis(heptafiuoroisopropoxy)- isopropyl acrylate-This compound was prepared in the same manner as described in Example 1,part -B, using 35 grams (0.6 mole) of anhydrous KF, 100 grams (0.6 mole)of hexafluoroacetone, 350 ml. of diglyme, and 36.4 grams (0.2 mole) of2,2-dichloroisopropyl acrylate. A 28% yield of ,the product wasobtained, B.P. 90-95 C. at 4-6 mm. Hg.

Example 3 Bulk polymerization of 2,3 bis(heptafluoroisopropoxy)-n-propylacrylate-A l-gram sample of the acrylate monomer was placed in a smallscrew-top vial together with 10 mg. of a,a'-azobisisobutyronitrile. Thevial was closed and heated at 80 C. for 3 hours. At the end of thistime, a clear, rubbery polymer had formed. It was insoluble innon-fluorinated solvents but could be dissolved in such solvents asl,3-bis(trifluoromethyl) benzene and dichlorotetrafluoroethane.

Example 4 Co-polymerization of 2,3-bis(heptafluoroisopropoxy)- n-propylacrylate with styrene.-A mixture of 2 grams of2,3-bis(heptafluoroisopropoxy)-n-propyl acetate, 0.5 gramof styrene, and20 mg. of a,oU-azobisisobutyronitrile was placed in a screw-top vial andheated at 80 C. for 3 hours. The resulting polymer Was dissolved in hotbenzotrifluoride and precipitated with methanol. The polymer was stifferthan the homopolymer of 2,3- bis(heptafluoroisopropoxy)-n-propyl acetateand dissolved more readily in benzotrifluoride than did the homopolymer.The inherent viscosity of a 1% solution of the copolymer in 1,3-bis(trifluoromethyl) benzene at 25 C. was 0.35.

Example 5 Emulsion polymerization of 2,2bis(heptafluoroisopropoxy)-isopropyl acrylate.-The following ingredientswere placed in a screw-top vial and agitated in a 45 C. water bath for 3hours:

2,2-bis(heptafluoroisopropoxy)-isopropyl acrylate, 5 g. H 0, 9 ml.

Sodium lauryl sulphate, 0.15 g.

A rubber polymer with an inherent viscosity of 0.4- 1% inl,3-bis(trifluoromethyl) benzene-was obtained by adding a saturatedaqueous solution of KCl to the polymer latex.

Example 6 Treatment of textiles with homopolymer of 2,3-bis(heptafluoroisopropoxy) 11 propyl acrylate.The homopolymer preparedas in Example 3 was dissolved in a mixture of1,Z-dichloro-tetrafluoroethane and 1,3- bis(trifluoromethyl) benzene,these solvents being in a proportion of 1 to 1 (by volume). Severalsolutions were prepared by appropriate dilution of a stock solution ofthe polymer.

Swatches of wool and cotton fabric were immersed in the polymersolutions, squeezed to ca. 100% wet pick-up, and placed in an oven at135 C. for 5 minutes. The cured swatches were then tested for oilandwater-repellency. The results are summerized below:

Concentration of polymer in Weight of Water treating polymer Oilrepellency repelsolution, on fabric, lency, percent percent Wool Cottonwe Example 7 Contact angles of hydrocarbons on glass slides coated withpolymer of 2-3-bis(heptafluoroisopropoxy) -n-propyl acrylate-In order todemonstrate the extreme oleophobicity of the poly acrylate, glass slideswere coated with a thin, smooth layer of the polymer by immersion in,and subsequent slow withdrawal from, a solution of the poly acrylatedissolved in a mixture of 1,3-bis(trifluoromethyl) benzene and1,2-dichlorotetrafluoroethane. Droplets of several pure hydrocarbonswere placed on the coated slides and the contact angle of the dropletsmeasured. These contact angles serve as direct measure of the resistanceof a surface to wetting, i.e., the larger the contact angle, the moreresistant is the surface to wetting by the test liquid.

The results obtained are summarized below:

Liquid applied: Contact angle deg.

Hexadecane 54 Decane 45 Octane 36 All of the above hydrocarbons ifapplied to an uncoated glass slide will spread out and wet the surface,i.e., give a contact angle of 0.

Example 8 Oil Water repellency repellency Treated wool 100 Untreatedwool 0 In our copending application Ser. No. 477,331, filed Aug. 4,1965, now Pat. 3,424,785, granted Jan. 28, 1969, we disclose compoundsof the structurewherein: R is H or CH; and m is an integer from 2 to 20.

The etherification procedure described hereinabove may be used toprepare these compounds and is an improvement over the synthesisdescribed in the prior application in that it is much simpler. To thisend, an adduct of hexafluoroacetone and an alkali metal fluoride isreacted with a monohaloalkyl acrylate or methacrylate. The

synthesis may be readily visualized from the following equation:

CF3 Mo-ilF R o 5 H CH2- -CO(CH2)mX In the above formulas, M is an alkalimetal, R is H or CH; m is an integer from 2 to 20, and X is Cl, Br, or1.

It is evident from the foregoing that that synthesis is a simpleetherification involving replacement of the halo group (X, above) by theheptafluoroisopropoxy group and elimination of alkali metal halide (MX).The desired etherification is accomplished simply by contacting thereactants. The temperature at which the reaction is conducted is not acritical factor and may vary, for example, from 20 to 150 C. Generally,temperatures of about 70- 100 C. are used to increase the rate ofreaction, yet without danger of decomposition. To avoid hydrolysis ofthe reactants, particularly the adduct, the reaction is carried outunder anhydrous conditions. To obtain good contact between thereactants, it is preferred to employ an inert solvent as, for example,acetonitrile, tetrahydrofuran, tetramethylene sulphone, dimethyl etherof diethylene glycol, etc. After completion of the reaction, the productmay be separated. by dropping the reaction mixture into an excess ofwater, separating the organic phase and subjecting it to distillationunder reduced pressure. The acrylic and methacrylic esters so producedmay be converted into polymers useful in treating of fibrous materials,as disclosed in the prior application Ser. No. 477,331.

This phase of the invention is further demonstrated by the followingexamples:

Example 9 Preparation of Z-(heptafluoroisopropoxy) ethyl acrylate.-

8 t OHz-OH-JJ-O-CHrCHz-O-CF A 3-necked, 250-ml., round-bottomed flaskwas dried and charged with 17.4 g. (0.3 mols) of anhydrous KF and ml.anhydrous diglyme. Fifty grams (0.3 mole) of hexafluoroacetone wasintroduced slowly and the mixture stirred. After formation of thehexafluoroacetone- KF add-net was completed, as evidenced by thedisappearance of dispersed KF, 38.5 grams (0.21 mole) of 2- bromoethylacrylate was added in one shot. The mixture was stirred and heated at 75C. for 20 hours. at the end of this time, the reaction mixture waspoured into 300 m1. of ice water.

The lower fluorocarbon layer was recovered, washed with water, driedover CaSO and distilled, giving 23 grams of pure product, B.P. 78 C. at47 mm. Hg, N 1.3424.

Example 10 wherein R is a member of the group consisting of H and CH thesaid compound being applied in an amount sulficient to enhance therepellency of the fibrous material, and

curing the impregnated fibrous material.

References Cited UNITED STATES PATENTS 2,803,615 8/1959 Ahlbrecht et a1.260-296 2,841,573 7/1958 Ahlbrecht et a1. 260-79.3 3,409,602 11/1968Anello et al 260-486 X WILLIAM D. MARTIN, Primary Examiner T. G. DAVIS,Assistant Examiner U.S.Cl.X.R.

P0405) UNITED STATES PATENT OFFICE 569 CERTIFICATE OF CORRECTION PatentNo. 3,518, 114 Dated June 30, 1970 Inventor(s) Allen G. Pittman et a1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

The formulas herein identified by column and line number should appearas shown below instead of as shown in the patent:

R 0 CF' I H 3 Column 2, lines 4-10: CH =C-C-O-(CH -CHCH -0-CF I I H CF ICF -C-CF F Column 2, lines 44-45: --CH --CH--CH --O- l Column 3, betweenCH -C-C-0-(CH -CH----CH -X lines 20 and 25: n u

Column Column Column Column Column Column 6, line 5:

9, lines 9-10:

9, lines 14-16:

9, line 55:

10, line 9:

10, between lines 30 and 35:

ll CH2-CH-C-O-CH -CH-CH -Br ca -c-c-o-(cup O-CF o CF3 N I cu -ca-c-o-cn-cu -o-cr l CF3 CH CH-COO-CH -C'H -Br WILLIAM E. BGHUYIMR, .m.Commission-er of Patent;

